The diff program is used to find differences between files. To know more about diff : http://www.google.com/search?hl=fr&q=man+diff
But, if we use diff in svn folder, it can find a difference between files inside .svn. Here is the line of code I’m using :
diff -r -x .svn /folder/source /folder/dest > file
With these parameters, diff doesn’t look into .svn folder.